74 CALIFORNIA ACADEMY OF SCIENCES. 



7 and 8 with pale longitudinal median band; last seg- 

 ment narrowly rounding, with a narrow emargination; 

 one short hair on the posterior margin, each side of the 

 emargination; ventral surface with broad transverse 

 median blotches, 



Male. Body, length 1.5 mm., width .4 mm.; head, 

 length .46 mm., width .34 mm.; distinctly shorter than 

 the female; abdomen more broadly elliptical; segments 

 7 and 8 narrowed distinctly in the middle; last segment 

 broadly rounded, with ten long hairs on the posterior 

 margin; transverse bands distinctly dark on segments 

 1 to 6; last segment evenly pale yellow; genitalia 

 darker brown, extending anteriorly to segment 5. 



Nirmus triangulatus Nitzsch. (Plate VI, fig. 2). 



Zeitschr. f. ges. Natiirwiss. (Giebel), 1866, vol. xxviii, p. 378. 



Nirmus normlfer Grube, v. Middeudorff's Sibir. Eeise, 1851, Zool. 



i, p. 478, pi. i, fig. 8. 

 Nirmus triangulatus N., Giebel, Insecta Epizoa, 1874, p. 177; Pia- 



get, Les Pediculines, 1880, p. 201, pi. xvi, fig. 5. 



Many specimens of this striking JS^irmus from one out 

 of two birds shot of the Pomarine Jaeger, Stercorarius 

 pomarinus (Bay of Monterey, California). Our speci- 

 mens differ from Piaget's figure in having the head dis- 

 tinctly shorter and narrower in front, giving the insect 

 an appearance markedly different from the effect given 

 by the figure. There is probably no doubt, however, 

 regarding the identity of the species. 



Nitzsch's specimens were taken from "Lestris crepi- 

 data," Grube's from ''Lestris richardsoni," and Piaget's 

 from Stercorarius pomarinus and Larus canus (Zool. 

 Garden of Rotterdam). 



The species may be readily recognized by the char- 

 acteristic black, subtriangular, lateral, abdominal 

 blotches, and the chestnut-brown, median, abdominal 



